Aftermarket Mustang Part Materials Explained

Whether you’re adding a spoiler to your Mustang or going for a full widebody kit, one of the first questions you should think about is what material your aftermarket parts will be made out of. Each of the materials used for aftermarket and performance Mustang parts has different strengths and weaknesses. Understanding what options are available for everything from your bumpers to your splitters and diffusers can help you decide what option is best for you.

Aluminum

Aluminum is used in a lot of vehicles, so it makes sense that many aftermarket parts are also made with this light metal. In addition to being light, aluminum is also recyclable and safe. Pound for pound, aluminum is one of the strongest and most durable metals.

Aluminum components have gained in popularity pretty dramatically with car manufacturers. They’re light, which creates a greater fuel efficiency, and though aluminum is more expensive than steel that gap is tightening rapidly.

There are some downsides to using aluminum though. It’s difficult and costly to repair aluminum parts. Aluminum is more susceptible to contamination than other metals which can lead to it causing strange chemical reactions in your paint. Considering the cost to exactly match paint colors, this is a significant downside for many customers. Subsequently, aluminum makes more sense for parts like a diffuser or splitter than a spoiler.

Fiberglass

Fiberglass is one of the most popular materials used in aftermarket parts. It’s anti-corrosive, resisting both the damage deicers can cause and also the problems associated with rust. It’s also light.

Fiberglass is a plastic that is reinforced with glass fiber. If glass fiber sounds a little strange to you, you’re not alone. But glass strands were produced accidentally when someone directed compressed air towards molten glass. The little fibers are incredibly useful for reinforcing substances, and have since been used in swimming pools, airplanes, roofs, and aftermarket car parts. Because the strands are so small, fiberglass is available in a variety of thicknesses.

The curious network of glass fibers allows for a stiff material that is also strong. There are some obvious benefits to this. For example, fiberglass won’t sag in heat the way plastics might. The stiffness is also its greatest weakness though. It’s essential for a fiberglass part to get fit exactly right since it can’t be adjusted and bent like plastic or metal, and in an accident fiberglass breaks.

Because of its fragility full fiberglass bodies aren’t a realistic option, but adding a fiberglass body kit can allow you to lighten your car without compromising on safety.

Because fiberglass is inexpensive and easy to make, there is a huge difference between "premium" fiberglass kits and some cheaper low-quality pieces. The low-quality parts have given fiberglass a bad reputation in terms of fit. A well-made fiberglass part should fit well.

Polyurethane

Polyurethane body parts tend to be inexpensive, and they offer the most flexibility of any of these materials. That means it’s easy to flex to create a perfect fit. The flexibility of polyurethane is also what gives it durability. Polyurethane parts will survive most minor accidents.

Unfortunately there are some downsides. For one, polyurethane is by far the heaviest material used to make aftermarket parts. The smoothness of polyurethane can make it more difficult than other materials to paint well, and the paint may flake off. Polyurethane is also susceptible to heat. Direct sunlight or solvents will both damage polyurethane more than other materials used for aftermarket parts, but parking it in a garage can cause problems because while the fumes it emits are slight and hard to notice outdoors, in an in-closed space they become more overbearing.

ABS Plastic

ABS plastic is known for its ability to stand up to heavy impacts and its ability to withstand both heat and cold.

ABS is a material with a huge variety of applications and exists not only in your car’s spoiler but also possibly in your tattoo. Some tattoo artists have moved to using inks with ABS because of the vibrancy of color that’s possible. You can also find ABS in 3d printers and legos.

Many car manufacturers use ABS Plastic to create the factory standard spoilers and body kits. Out of all of these ABS is one of the easiest options to ‘fit’ and is frequently used for trim, bumper covers and some body panels.

One negative to consider is that at extreme heat (like, 752 degrees Fahrenheit extreme) ABS plastic will break down into its components, one of which can cause cancer. Quite frankly though, if the ambient temperature is 752 degrees you have other concerns that are much more pressing.

In order to shape ABS plastic into a part that can fit your car, it has to be mixed with something, usually granular fillers. This makes the material stiff, but it can cause the parts to break down with age. ABS parts don’t always age well, especially if asked to withstand weather. ABS parts also do not fare well when forced to deal with chemicals and are likely to break down.

Carbon Fiber

Each individual carbon fiber is impossibly thin. Then several thousand fibers are wound into a yarn. Then the yarns are woven into a fabric and combined with epoxy, which allows it to be molded into a shape, like a spacecraft part or a hood for your Mustang. Though some think of it as ‘new’ and it is, relatively, carbon fiber has been around for over 60 years. Originally, carbon fiber was used to reinforce missiles in the 50’s.

If it’s good enough for missiles and spacecraft, it’s a safe bet that it’s good enough for your Mustang. Carbon fiber is very strong, light and expensive.

Carbon fiber is typically used in high-end vehicles associated with racing. This is due to carbon fiber’s incredible lightness. In terms of strength to weight ratio, carbon fiber really is in its own class.

Vipers, Shelbys, and Corvettes all are available now with a carbon fiber aero package. The Shelby GT350R is almost sixty pounds lighter than its brethren, allowing it to corner like no other. Very few cars are made entirely out of carbon fiber, though Ford is planning on releasing a special carbon edition of the next GT that will be made out of carbon fiber.

The major downside to carbon fiber is the cost. As explained, making carbon fiber takes a lot of steps and is very involved. It’s also the newest of these materials and there is a premium price on new. Right now, carbon fiber costs approximately sixteen dollars per a pound to create, and that’s before any shaping or designing takes place. Contrast that to a dollar per a pound of steel and you’ll understand why carbon fiber bodies haven’t taken off.

There are companies working to drive down the price of carbon fiber, and discovering ways that carbon fiber can benefit manufacturing in a way that will make it more cost effective. Even taking these discoveries into account carbon fiber would have to drop down to five dollars a pound in order to be competitive. In the meantime,carbon fiber aftermarket parts are available either for people who are drawn to the durability or the lightness.

There are other downsides of carbon fiber that should certainly be discussed. Unlike steel which is easy to repair, carbon isn’t. If you’re in an accident where a carbon fiber part is damaged, then it’s toast. And given the high cost of carbon fiber parts, it’s not an insignificant loss. It also isn’t a material that can be reused, it loses its durability after even one iteration making recycling impossible.

Composites

Composites are literally mixes of one or more substances. Fiberglass is itself a composite, but it’s also a material used to make other composites. You’ll frequently see carbon fiber pieces that are partially fiberglass for example. Carbon fiber wheels are popular, but also exceptionally pricey, coming in at nearly $10,000 for a full set. On the other hand, a magnesium alloy wheel with a carbon fiber facing is a great middle ground and reduces the price significantly.

Composites allow manufacturers to offer a blend of different substances that hopefully offers the benefits of multiple substances at once. So, the look of carbon fiber without the price tag.

These blends do tend to be proprietary in nature. One of the most well-known composites is Duraflex. When shopping composites, it’s important to read what each is a blend of. Duraflex’s manufacturers are upfront about the fact that Duraflex is a fiberglass/plastic composite which shatters less than fiberglass but that will not bend the way urethane does. It’s important to take note of these details when evaluating a part for your individual needs to isolate what features you really need to make your build your own.

The great thing about all of these substances is that you can mix them as you will in your build. Whether you really want carbon fiber wheels but a polyurethane bumper or a fiberglass spoiler, it’s all up to you and customizable based on your ideal build and usage. None of these is the solution for one hundred percent of car modders one hundred percent of the time.

By knowing the strengths and weaknesses of each body material, you set yourself up to make the best Mustang for you, which is the goal of every Mustang enthusiast.

Body kits come in a wide variety of materials. Everything from tried and true fiberglass to the impossibly good carbon fiber is worth considering depending on what direction you're planning on taking your Mustang's build. This guide explains the pros and cons of some of the most common body kit materials, including fiberglass, polyurethane, ABS, carbon fiber and composites.